In recent years, progress has been made in the research and development of display devices that use the phenomenon of electroluminescence occurring in organic material. Each light-emitting cell of such a display device is composed of an anode and a cathode with an organic light-emitting layer therebetween. When the display device is driven, holes are injected through the anode, electrons are injected through the cathode, and the holes and electrons recombine within the organic light-emitting layer, thereby emitting the light.
The organic light-emitting layer is formed by dripping ink that includes organic light-emitting material into regions separated by banks composed of insulating material and then drying the ink. The thickness of the organic light-emitting layer exhibits a correlation with luminance. Therefore, it is desirable to maintain the thickness of the organic light-emitting layer as uniform as possible.
To satisfy this desire, technology has for example been proposed to provide a gap between the bank and the anode provided therebelow in order to balance affinity and repellency in order to achieve uniformity in the thickness of the organic light-emitting layer (Patent Literature 1). Technology has also been proposed to apply surface treatment, such as oxygen plasma treatment, to the surface of the layer beneath the organic light-emitting layer and to apply surface treatment, such as CF4 plasma treatment, to the surface of the bank in order to achieve uniformity in the thickness of the organic light-emitting layer formed in regions surrounded by these surfaces (Patent Literature 2).